铝合金在多级脉冲电磁成形中的成形性能研究及变形行为预测

Electromagnetic forming is a promising forming method in aerospace and automobile manufacturing, as it can increase the formability of the material, reduce the spring-back and improve the surface quality of the work-piece. With the limit of the power energy density, a multi-pulse electromagnetic forming process in which the multi-pulse discharging is employed to carry out the forming is proposed here. Combined the simulation and experiment, the formability and deformation behavior of the aluminum alloy in the multi-pulse electromagnetic ring expansion will be studied, the effect rule of the induced current, temperature, strain rate, strain history and their coupling on the formability will be revealed, and the constitutive relationship of the aluminum alloy will be clarify in this research. Based on the constitutive model, a simulated forecast model is then set up for the prediction of the deep drawing of the aluminum alloy sheet during the multi-pulse electromagnetic forming, and these will provide the theoretic foundation and evidence for the design and optimization of the multi-pulse electromagnetic forming.

电磁成形加工方法具有提高材料成形极限、减小回弹、改善表面质量等一系列优势，有望突破现有铝合金成形制造的瓶颈，在航空航天及汽车制造等诸多领域具有广阔的前景。针对常规电磁成形中厚板件深拉伸所需电源能量密度大、装备复杂等问题，本项目提出了多级脉冲电磁成形技术，利用重频脉冲放电来完成工件的深成形。项目围绕多级成形铝合金材料本构关系这一关键科学问题，建立多级脉冲电磁成形仿真分析模型和电磁胀环实验平台，研究多级脉冲胀环过程中铝合金的成形性能与变形行为，揭示感应涡流、温度、应变率、应变历史及其耦合作用对铝合金成形性能的影响规律，实现多级脉冲电磁成形过程中铝合金工件变形行为的预测，为铝合金多级脉冲电磁成形过程的设计与优化提供理论基础及依据。

电磁成形技术具有提高材料成形极限、减小回弹、改善表面成形质量等一系列优势，是解决现有铝合金成形制造瓶颈的重要方法之一，在航空航天及汽车制造等诸多领域具有广阔的前景。但常规电磁成形中板件深拉伸对成形电源及驱动线圈等装备要求较高，提高系统能量利用率及工件成形效果是电磁成形技术发展的重要任务之一。本项目根据电磁胀环数值仿真及实验研究，构建了适用于脉冲电磁成形的铝合金材料本构方程，表征脉冲电磁成形过程中铝合金材料流动应力应变之间的对应关系。在此基础上，我们应用COMSOL多物理场耦合仿真软件搭建了脉冲电磁成形数值仿真模型，对电磁成形过程进行详细的分析，就多场耦合作用机制及电磁力特性开展研究，就放电电路、线圈结构、线圈与工件相对位置关系等过程参数对成形深度的影响进行分析与研究。此外，结合仿真与实验，我们还对铝合金板件在多级脉冲电磁自由胀形及多级驱动冲压成形过程中的成形特性进行了研究与预测。本项目的研究为成形装置及成形过程的优化设计提供了基础与依据。